The invention relates to a projectile, particularly for shooting from a smooth barrel, comprising guide members and/or a propulsion member, which separate from the projectile body after leaving the barrel.
The projectile according to the invention can be one having a sub-calibre solid projectile body or a calibred or sub-calibre tubular projectile body. Further, it may be with or without steering gear.
In so far that the projectile according to the invention comprises guide members, these can be of the known kind consisting of a cage or of rings by which the body of the projectile is surrounded with a positive fit. The cage as well as the rings will in that case preferably comprise a plurality of releasably interconnected segments or segments that are merely interconnected by frangible portions. The propulsion member of the projectile is as usual disposed between the front end of the propellant container and the rear of the projectile body without being permanently connected to the latter. It may be of one or more parts. Further, it is possible to combine it with the guide members to form a unit.
Projectiles of the kind in question are not only provided for sharp shooting but they are also used to a large extent as so called training projectiles for target practise.
It is desirable to propel such projectiles with a spin, the extent of spinning being adapted to the departure and flight properties of a particular type of projectile, and to obtain spinning even when shot from a smooth barrel.
In the case of aerodynamically unstable projectiles, spinning is particularly desirable for obtaining flight stability of the projectile. The rotary speed about the longitudinal axis of the projectile, also termed trajectory flatness, is given by the shape and mass geometry of the projectile body when released from its guide members and its propulsion member. At the same time, spinning favours the trouble-free separation of laterally flung guide members after the projectile leaves the barrel.
It is known that projectiles of the stated kind can have a spin imparted to them in the barrel by providing the latter with so-called rifling. In this case the projectile has an excess dimension on at least part of its peripheral surface, so that, upon firing, it is first pressed into the rifling and then follows the rifling almost with a positive fit. With this method of producing the spin, the extent of spinning on departure is given by the angle of the rifling in the barrel and the muzzle velocity of the projectile. This fact makes any kind of spin control impossible if one wants to fire different projectile shapes from one end and the same barrel or obtain different muzzle velocities, as is desired in the case of target practise and may also be desirable for sharp shooting. As a result, one obtains defective flight and target behaviour of the projectile body.
However, projectile shapes have also become known wherein the projectile is made in one piece and is provided on its outer wall or in the interior with so-called spin passages. On firing, these passages are penetrated by the propellant gases and they permit projectiles to be shot from smooth barrels with a spin. By appropriately shaping the passages, they also permit selection of the trajectory flatness independently of the muzzle velocity of the projectile. However, the projectile constructions in question have not proved successful because of their external ballistic problems and because of an unfavourable shape of their spin passages.
Smooth barrels are currently used only to shoot projectiles having guide members and/or a propulsion member; they leave the barrel without spin and are equipped with steering gear for stabilising their flight. An inherent risk of steering gear is that the projectile body is not separated from the guide members without any impact. In addition, steering gear makes the projectile supersensitive to the powder gas impinging on the rear of the projectile during departure. Steering gear that falls open has the inherent additional danger of malfunctioning. These constructions of projectiles are not only liable to become defective but also expensive to produce and therefore not very suitable for practising purposes.